The goal of this project is to determine whether applied apical torsion can be used as a means to assist the failing heart without contacting the blood. This novel approach to heart failure treatment is aimed at augmenting the normal twisting motion of the ventricles, which is an important contractile component often missing in diseased hearts. If this method proves effective, it could be used for both short-term and chronic cardiac support without the hematologic risks associated with blood-contacting devices. This technology has the potential to improve patient outcomes and lower overall health care costs by providing a simple and inexpensive means of mechanical circulatory support. The advantages of this approach are several. First, a torsion-based ventricular assist device (tVAD) could be applied quickly without the need for invasive cannulae or dangerous and expensive anticoagulation drug therapy. Another advantage is that tVAD operation could be stopped for brief (or even extended) periods of time and started up again without risking thromboembolic complications that preclude such on/off cycling in conventional blood pumps, which must be removed or replaced if stopped for more than a few minutes. Also of significance is the fact that the most costly components needed for acute tVAD support would be reusable, thus allowing hardware costs to be spread out over a large number of patients. Preliminary studies show that supraphysiologic torsion-90 degrees or more- can be applied to the heart during systole without causing arrhythmias, whole-heart rotation, or tissue damage. Though encouraging, these early results are limited in that as they were obtained for short periods of time using a non-optimized torsion apparatus applied to small hearts with normal ventricular geometry. There is strong incentive, therefore, to expand upon these studies in order to establish the extent to which tVAD technology can be used as an effective means to improve cardiac function in heart failure patients. The principal objectives of this project are to assess the feasibility of this approach ad determine the conditions under which mechanical apical torsion can best be used to assist the failing heart. To achieve these objectives, we propose to pursue the following two specific aims: 1) Develop and implement an advanced bi- ventricular computer model to simulate the effects of various torsion parameters on ventricular function in the setting of cardiogenic shock and chronic heart failure; and 2) Test prototype devices in vivo to measure the effects of applied apical torsion on valve competency, determine whether the device causes myocardial tissue damage, and quantify the therapeutic benefit in the setting of severe heart failure. Our expectations are that, at the conclusion of the proposed period of support, we will have determined which form(s) of heart failure are most amenable to tVAD therapy and what mode(s) of apical torsion-percent cardiac coverage, twist angle, torsion speed, etc.-produce the best results. We further expect to have demonstrated the effectiveness of this approach experimentally using a prototype tVAD in an animal model of heart failure.